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Regulation of chorismate mutase, prephenate dehydrogenase and prephenate dehydratase of Candida maltosa
Author(s) -
Bode R.,
Melo C.,
Birnbaum D.
Publication year - 1985
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.3620250502
Subject(s) - chorismate mutase , biochemistry , tryptophan , dehydratase , stereochemistry , chemistry , tyrosine , enzyme , biosynthesis , amino acid
The enzymes of the phenylalanine‐tyrosine pathway were partially purified from Candida maltosa and the regulatory patterns were established. Chorismate mutase (Mr 63,000), prephenate dehydrogenase (M r 75,000) and prephenate dehydratase (M r 88,000) were separated from each other. The formation of chorismate mutase was only regulated by a general control of amino acid biosynthesis, whereas the synthesis of prephenate dehydrogenase and prephenate dehydratase was constitutive. Both chorismate mutase and prephenate dehydrogenase were activated by tryptophan and by methylated or fluorinated tryptophan analogues. l‐tyrosine as well as α‐methyl‐dl‐tyrosine inhibited the activity of both enzymes. Prephenate dehydratase activity was stimulated by l‐tryptophan and by methylated tryptophan derivatives and inhibited by d‐tryptophan or 5‐fluorotryptophan. In contrast to chorismate mutase, the double‐reciprocal curves of substrate saturation of which were hyperbolical (positive cooperativity), prephenate dehydrogenase and prephenate dehydratase showed linear curves of substrate saturation, indicating normal Mi‐chaelis kinetics.